Allergic conjunctivitis — the itchy-eye side of allergy

In brief

• Allergic conjunctivitis is the eye version of the allergy behind allergic rhinitis, in Singapore usually triggered by house dust mite.
• Itch is the main symptom, and it is not an infection or contagious.
• Cold compresses, artificial tears and not rubbing all help.
• Dual-action drops such as olopatadine or ketotifen are first-line and take a few days to a week to work fully.
• Avoid regular “red eye relief” drops; antibiotic drops are not needed.
• See a doctor if only one eye is affected, your vision changes, the discharge is thick and coloured, or drops haven’t helped after 2 weeks.

We assess and treat eye allergy in adults and children at our Punggol clinic. Book an appointment.

Does this sound familiar?

A story we often hear from parents of young children:

“By about 10 in the evening, she starts rubbing her eyes red with her knuckles and hands. Some mornings her lashes are stuck together with crust in the corners. She says it doesn’t hurt; her eyes just ‘feel funny’. This has gone on for months. Her kindergarten teacher keeps asking if it’s an eye infection.”

Or from an adult:

“My eyes itch all the time and water when I wake up. If I touch them, it flares for half an hour. I’ve tried every eye drop at the pharmacy. Some help for an hour or two, then it’s back.”

Both are classic allergic conjunctivitis. Typical features:

• Itch is the main symptom, not pain.
• Symptoms peak in the evening and early morning, after a day of exposure and a night on the pillow, where dust-mite allergen concentrates.
• Rubbing brings brief relief but makes things worse for the next hour or two.
• Morning crusting from overnight discharge, usually clear or whitish rather than the thick yellow-green of a bacterial infection.
• Symptoms come and go over weeks or months, rather than clearing in 7–10 days like a viral infection.
• Nasal symptoms often come too, even mild ones like morning sneezing or a stuffy nose in bed.

Eye-rubbing is often the first thing parents notice. Take it seriously: children can rub hard enough to scratch the cornea and, in severe allergic eye disease, cause structural damage.

What is allergic conjunctivitis?

It is the “eye version” of the allergic process that causes a runny, itchy nose and sneezing in allergic rhinitis. The two coexist in roughly 60–75% of atopic patients and are often grouped as “allergic rhinoconjunctivitis”.

The conjunctiva is the thin, clear lining over the white of the eye and the inside of the eyelids. Like the nasal lining, it is rich in mast cells, immune cells that release histamine when they recognise an allergen. In Singapore the allergen is most often house dust mite. The result:

• Itching, the key symptom. Without itch, allergic conjunctivitis is unlikely.
• Redness (conjunctival injection: visibly dilated blood vessels)
• Tearing and watering
• Mild swelling of the conjunctiva (chemosis) or eyelids
• A gritty, foreign-body feeling, not true pain
• Clear or whitish discharge, usually worst on waking

It is not an infection. You cannot catch it, and your child cannot pass it to classmates. Mistaking it for one leads to needless time off school, antibiotic drops and worry.

How we recognise it on examination

We typically see:

• Conjunctival injection: redness, usually diffuse, often more marked in the lower and inner parts of the eye
• A papillary or follicular pattern inside the eyelids (the tarsal surface): tiny raised bumps from inflamed lymphoid tissue
• Allergic shiners: darker skin under the eyes, from slowed venous drainage around the inflamed area
• Dennie–Morgan lines (sometimes): extra horizontal creases below the lower eyelids, a classic atopic sign
• Periorbital puffiness (mild swelling around the eye)
• Clear, watery discharge, sometimes with a few whitish strands, unlike the thick yellow-green of bacterial conjunctivitis

We usually don’t need special tests. The story and examination make the diagnosis.

Types of allergic conjunctivitis

• Perennial allergic conjunctivitis (PAC): year-round, driven by indoor allergens (house dust mite, moulds, pet dander). This is by far the commonest form in Singapore and usually pairs with perennial allergic rhinitis.
• Seasonal allergic conjunctivitis (SAC): follows the seasons, usually from pollen. Uncommon in Singapore, but seen in people who spent years in temperate countries.
• Contact allergic conjunctivitis: caused by something touching the eye, such as cosmetics, eye make-up, contact lens solution, or preservatives in eye drops (benzalkonium chloride is a common culprit). It usually settles within a week or two once the trigger is removed.

Most cases we see are perennial and dust-mite-driven, and respond well to the treatment below.

What’s triggering it in Singapore

The triggers are the same as for allergic rhinitis (details in the allergic rhinitis guide):

• House dust mite dominates. Over 80% of atopic people in Singapore are sensitised.
• Pet dander in pet-owning homes
• Moulds in damp, poorly ventilated areas
• Irritants that worsen symptoms without being true allergens: cigarette smoke, strong perfume, incense, chlorinated pools, air-conditioning blowing at the eyes
• Contact triggers: eye make-up, eye-drop preservatives, contact lens solutions, skincare that migrates into the eye during sleep

If dust mite drives your nose symptoms, the same bedroom measures help your eyes: dust-mite-proof bed covers, hot-washed bedding and less clutter.

Why treat it — what you get back

Many people put up with itchy eyes for years, using whatever “red eye” drop is nearest. Proper treatment usually brings:

• Mornings without stuck lashes or a gritty start
• Fewer tension-type headaches from constant squinting and irritation
• Better concentration and screen tolerance, at work and at school
• Fewer bacterial infections, since rubbing breaks the eye’s defences and can introduce bacteria
• Less risk of corneal damage from rubbing, especially in children
• Contact lens wear again, for people who gave up lenses because of irritation
• Better overall allergy control, since eye and nose share the same allergic drive

Treatment — practical options

Non-drug measures (do these regardless of medication)

• Cold compresses work well. A clean, cool, damp cloth over closed eyes for 5–10 minutes reduces itch and swelling, even more if chilled in the fridge. For children, a cool gel eye-mask from a pharmacy is easy to use.
• Preservative-free artificial tears (single-dose vials, used through the day) wash allergen off the eye, dilute inflammatory chemicals and ease grittiness. Local brands include Systane UD, Refresh Plus, Tears Naturale Free and Hyabak.
• Avoid rubbing. Rubbing eases itch for a moment, but within minutes it makes mast cells release more histamine, and the itch returns worse. Use a cold compress, a splash of cool water or a drop of artificial tears instead.
• Wash your face before sleep to remove pollen, dust and skincare or make-up residue around the eyes.
• Reduce triggers with bedroom dust-mite measures (see the AR guide), since bedding is where overnight exposure happens.
• Check your eye make-up. Mascara, eyeliner and false-lash glue are common hidden causes in women. A two-week break often settles things.

First-line: dual-action eye drops

These drops both block histamine and stabilise mast cells, so less histamine is released in the first place. They act faster than pure mast cell stabilisers and last longer than pure antihistamine drops. They are now the standard first-line treatment.

Commonly used in Singapore:

• Olopatadine 0.1% (Patanol): twice daily, registered for children from 3 years of age
• Olopatadine 0.2% (Pataday): once daily, as the higher strength lasts longer; also registered from 3 years
• Ketotifen 0.025% (Zaditen): two to three times daily, registered from 3 years

Other dual-action drops (epinastine, bepotastine, alcaftadine) are used internationally, but availability in Singapore varies.

Worth knowing:

• They take a few days to a week of regular use to work fully, so give them time.
• Use them twice daily (once for Pataday), ideally morning and evening.
• They are safe for long-term daily use, and we often prescribe them for months at a time.
• Bottles usually contain a preservative (benzalkonium chloride). This is generally fine but can irritate very sensitive or dry eyes. Preservative-free single-dose versions exist in some regions; ask us.
• Don’t let the bottle tip touch the eye or lashes, to avoid contamination.

Oral antihistamines — a supporting role

Second-generation antihistamine tablets (loratadine — Clarityn; cetirizine — Zyrtec; fexofenadine — Telfast; bilastine — Bilaxten) are very useful when nose and eye symptoms occur together, which is most of the time. For eye symptoms alone they are less effective than eye drops. Via the bloodstream, the drug reaches the eye more slowly and in lower concentration.

Our usual pattern:

• Eye symptoms only → dual-action eye drops
• Eye and nose symptoms → nasal corticosteroid spray + dual-action eye drops, with or without an oral antihistamine
• Nose symptoms only → nasal corticosteroid spray ± oral antihistamine (see the AR guide)

Oral antihistamines, especially cetirizine and levocetirizine, can occasionally dry the eyes. If your eyes feel gritty rather than itchy, switching antihistamine sometimes helps.

A note on sodium cromoglycate

Sodium cromoglycate eye drops (Allergocrom, Opticrom) were for many years the standard children’s option: a pure mast cell stabiliser with an excellent safety record. Allergocrom is no longer widely available in Singapore. Dual-action drops have largely replaced it, with better effect: usually olopatadine (Patanol/Pataday) or ketotifen (Zaditen), both registered for children from 3 years.

What we generally don’t recommend

• “Red eye relief” decongestant drops: tetrahydrozoline (Eye-Mo, Visine), naphazoline (Naphcon). They whiten the eye quickly by shrinking blood vessels but don’t treat the allergy. Used beyond a few days, they cause rebound redness as they wear off and a cycle of dependence. This “conjunctival medicamentosa” mirrors rhinitis medicamentosa from nasal decongestants. Occasional use for a wedding or meeting is fine; regular use isn’t.
• Antibiotic eye drops (chloramphenicol, tobramycin, gentamicin, fusidic acid): often prescribed for “pink eye”, but unnecessary here because this is not an infection. Overuse promotes resistance and can cause contact allergy to the drops. We use them only for genuine bacterial conjunctivitis.
• Long-term use of any eye drop without review. Even safe drops should be reviewed periodically.
• Rubbing to “clear” the eye. It helps for seconds and worsens things for hours.

Children — age-specific notes

Giving eye drops to a resistant child

Techniques that work:

• Lie your child flat on their back with eyes gently closed. Place a drop in the inner corner of the closed eye. When they open their eyes, the drop rolls in.
• For older children (5+): with the child sitting and looking up, gently pull the lower lid down and place the drop in the pouch.
• Don’t chase a moving target. Hold the bottle close without touching, and place a single drop; one is enough.
• Reward and routine help. Morning and bedtime drops soon become part of the day.

School and childcare — allergic conjunctivitis is not contagious

• Allergic conjunctivitis is not infectious. Your child does not need to be kept out of school or childcare, and nobody will catch it.
• If a teacher still sends your child home, ask for a note to be kept on file, or we can provide one.
• Signs it is not an infection: itch rather than pain; clear rather than thick coloured discharge; both eyes rather than one; a chronic or recurrent pattern rather than a 1-week acute episode.

Contact lens wearers

• Allergic conjunctivitis and contact lenses don’t mix well. During a bad allergy spell, switch to glasses. Lenses trap allergen against the cornea and often worsen the reaction.
• Preservatives matter. Benzalkonium chloride, in many drops, builds up on soft lenses and can irritate. For drops with lenses in, preservative-free single-dose versions are worth the cost.
• Lens hygiene is essential. Chronic allergic conjunctivitis raises the risk of a lens-related infection. Never rinse lenses in tap water, always use fresh solution, and replace the case regularly.
• Giant papillary conjunctivitis: large bumps (papillae) form inside the upper lid from the rubbing of a contact lens. It causes lens intolerance, ropy mucus and itch that worsens with lens wear. Treatment starts with a break from lenses, plus dual-action drops. A different lens type is often needed afterwards.

Pregnancy

Very little of an eye drop is absorbed into the body, so drops are generally safer in pregnancy than tablets. A reasonable approach:

• Cold compresses and preservative-free artificial tears: safe throughout pregnancy and a useful first step
• Olopatadine and ketotifen eye drops: limited human data, but absorption is minimal and they are generally considered acceptable when needed
• Sodium cromoglycate drops (where available): a long safety record
• Avoid decongestant “red-eye” drops
• Oral antihistamines: loratadine and cetirizine have the most reassuring data; discuss with us

When to come in

Allergic conjunctivitis rarely needs same-day care, but please book a visit if:

• Over-the-counter drops haven’t settled symptoms after 2 weeks of regular use
• Symptoms are in one eye only and persist; one-sided problems need a look
• You wake with thick coloured discharge that sticks the lids together, rather than mild crusting. This may mean an infection on top.
• Your vision has changed: blurring that doesn’t clear with blinking, trouble in bright light beyond mild squinting, or seeing halos
• Your child is rubbing hard enough to hurt themselves, or has developed sensitivity to light (photophobia)
• You wear contact lenses and symptoms worsen with lens wear

The Singapore context — schemes that help

• Healthier SG Chronic Tier: enrolled patients can get chronic-disease consultations and some medicines at subsidised rates
• Community Health Assist Scheme (CHAS): means-tested subsidies for consultations and selected medicines at participating GP clinics
• MediSave: usable for chronic disease consultations, up to the annual withdrawal limit

For chronic care, allergic conjunctivitis usually sits under the “allergic rhinitis and its impact on asthma” umbrella. If you are enrolled with us for rhinitis, we review and manage your eye symptoms within that plan.

Get in touch

Punggol — 658 Punggol East, #01-04, Singapore 820658 · Tel 6312 4589

Joo Chiat — 172 Joo Chiat Road, #01-01, Singapore 427443 · Tel 6920 1952

Email — admin@ktmc.sg

References

Guidelines and reviews

• Bousquet J, Schünemann HJ, Togias A, et al. Next-generation Allergic Rhinitis and Its Impact on Asthma (ARIA) guidelines for allergic rhinitis based on Grading of Recommendations Assessment, Development and Evaluation (GRADE) and real-world evidence. J Allergy Clin Immunol. 2020;145(1):70-80. (Covers allergic rhinoconjunctivitis together.)
• Dupuis P, Prokopich CL, Hynes A, Kim H. A contemporary look at allergic conjunctivitis. Allergy Asthma Clin Immunol. 2020;16:5. doi.org/10.1186/s13223-020-0403-9
• American Academy of Ophthalmology. Preferred Practice Pattern — Conjunctivitis. 2023 update. aao.org

Dual-action eye drops

• Abelson MB, Gomes P, Crampton HJ, Schiffman RM, Bradford RR, Whitcup SM. Efficacy and tolerability of olopatadine 0.2% in the treatment of allergic conjunctivitis. Curr Med Res Opin. 2007;23:1221-1232.
• Greiner JV, Mundorf T, Dubiner H, et al. Efficacy and safety of ketotifen fumarate 0.025% in the treatment of seasonal allergic conjunctivitis. Acta Ophthalmol Scand. 2003;81(5):495-504.

National programmes

• Ministry of Health, Singapore. Healthier SG and Chronic Tier information. healthiersg.gov.sg
• Community Health Assist Scheme. chas.sg

This information is for general education only and is not a substitute for medical advice. Allergic conjunctivitis management should be individualised to your symptom pattern, triggers, and any coexisting conditions — please speak with our team. v1.1 · October 2026 (v1.0 April 2026) · Review due April 2028.